Weather in September
Temperature
Entering September, Portsmouth's average high-temperature reads an enjoyable 19°C (66.2°F), indicating a close resemblance to the previous month's climate. Portsmouth experiences an average low-temperature reading of 12.2°C (54°F) throughout September.Rainfall
In Portsmouth, during September, the rain falls for 8.5 days and regularly aggregates up to 54mm (2.13") of precipitation. Throughout the year, in Portsmouth, there are 103.4 rainfall days, and 699mm (27.52") of precipitation is accumulated.Sea temperature
September is the month with the warmest seawater, with an average sea temperature of 17.3°C (63.1°F).Note: Swimming is not an enjoyable activity for the majority when the water is at 17.3°C (63.1°F). The difficulty of controlling breathing increases as the temperature dips from 21°C (69.8°F) to 15°C (59°F).
Daylight
The average length of the day in September is 12h and 37min.On the first day of the month, sunrise is at 6:19 am and sunset at 7:49 pm. On the last day of September, sunrise is at 7:04 am and sunset at 6:44 pm BST.
Sunshine
In Portsmouth, the average sunshine in September is 5.8h.UV index
In Portsmouth, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from unprotected exposure to Sun's UV rays for average individuals.Note: A maximum high UV index of 4 in September translates into the following recommendations:
Be mindful. Those with pale skin might receive burns in fewer than 30 minutes. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. Outfit yourself in sun-safe attire, like long sleeves, pants, a hat, and UV-blocking sunglasses.
Frequently asked questions
What is the temperature in September in Portsmouth?
How much does it rain in Portsmouth in September?
What month is the sea warmest in Portsmouth?
What is the sea temperature in September in Portsmouth?
What is the average length of the day in September in Portsmouth?
When is the sunrise / sunset in September in Portsmouth?
How long on average sun shines in September in Portsmouth?
How high is the UV index in September in Portsmouth?
Average temperature in September
Portsmouth, United Kingdom
- Average high temperature in September: 19°C
The warmest months (with the highest average high temperature) are July and August (21.4°C).
The months with the lowest average high temperature are January and February (8.2°C).
- Average low temperature in September: 12.2°C
The month with the highest average low temperature is August (14.3°C).
The coldest month (with the lowest average low temperature) is February (2.8°C).
Average rainfall in September
Portsmouth, United Kingdom
- Average rainfall in September: 53.7mm
The wettest month (with the highest rainfall) is October (86.2mm).
The driest month (with the least rainfall) is June (42mm).
Average rainfall days in September
Portsmouth, United Kingdom
- Average rainfall days in September: 8.5 days
The months with the highest number of rainy days are January and December (11.2 days).
The month with the least rainy days is July (5.4 days).
Average sea temperature in September
Portsmouth, United Kingdom
- Average sea temperature in September: 17.3°C
The best month for swimming (with the highest average sea temperature) is September (17.3°C).
The coldest month (with the lowest average sea temperature) is March (8.6°C).
Average daylight in September /
Average sunshine in September
Portsmouth, United Kingdom
- Average daylight in September: 12h and 4min
The month with the longest days is June (Average daylight: 16h and 24min).
The month with the shortest days is December (Average daylight: 8h and 0min).
- Average sunshine in September: 5h and 5min
The month with the most sunshine is July (Average sunshine: 8h and 24min).
The month with the least sunshine is December (Average sunshine: 2h and 0min).
Average UV index in September
Portsmouth, United Kingdom
- Average UV index in September: 4
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 1).
Portsmouth, United Kingdom
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